At my last gig we had three support channels: phone, skype and ticketing. Standard workflow (which clients always tried to circumvent) was: client writes to sky

At my last gig we had three support channels: phone, skype and ticketing. Standard workflow (which clients always tried to circumvent) was: client writes to skype/calls, we decide whether complaint is solved by a quick explanation and respond with a call, or problem requires more investigation/work and client is directed to submit a ticket.